The heirs to The Greatest Show on Earth are apparently experiencing what is perhaps the saddest trial on earth. It involves two siblings whose father has brought wonder and amazement to generations of children.

Karen Feld, 63, is suing her younger brother Kenneth, 62, for $110 million for assault. But the litigation has its roots in the estrangement of the two offspring of Irving Feld, who owned Ringling Bros. and Barnum & Bailey Circus. Feld groomed his son for the family business from a young age, but his will cut his daughter out of it more than two decades ago.

The late multimillionaire owned Feld Entertainment, which Kenneth now runs, and its holdings include Disney on Ice, drag racing and monster truck shows. But the younger Feld is fiercely private about the family, and in his sister’s lawsuit he is accused of trying to control his sister for fear she will reveal damaging secrets about their father, according to an Associated Press report.

Karen Feld said her brother had bodyguards attack her and throw her out of their aunt’s bereavement ritual, inflicting injury that required surgery. Kenneth Feld has filed a counterclaim for trespassing.

But the brother and sister battle is said to be the latest in a long history of conflict between the two that includes multiple lawsuits and even an explosive confrontation at an Arlo Guthrie concert. Kenneth is even said to have hired an ex-CIA operative to spy on a journalist who had written an article on the family in 1990, whose information he believed Karen had supplied. The operative allegedly went as far as becoming her editor and diverting her professional work to other projects.

The two stories behind altercation at their aunt’s shiva rite are as radically different as the two siblings. Karen said that she began to suffer a seizure, which she has a history of, and her brother sent men after her to beat her and throw her out of the ceremony, causing numerous injuries. But Kenneth says when a guard went to her, she began to swing at him and denies the guards beat her at all, and actually claimed assault against her, but later dropped it.

U.S. District Judge Ellen Seagal Huevelle will hear the trial beginning Monday. “It is hard to believe that we could come from the same parents genetically and be so different and that a brother could do this to his only sister,” Karen Feld told the AP. Kenneth Feld declined to be interviewed.